1. Field of the Invention
The present invention relates to clock signal generators, and particularly to a generator for generating an adjustable and stable rectangular waveform.
2. General Background
The role of a clock signal in a network is to distribute a common frequency throughout the network to provide synchronization in the network. A range within which the frequency is distributed depends on the basic configuration of the network. A network of a network synchronization type is constructed in the case of a long distance communications system. In the network of the network synchronization type, a single master station or quasi-master station distributes a clock signal at the reference frequency (hereinafter, referred to as the reference clock signal), and the reference clock signal is played back in every node within the network. In this system, all the circuits within the network use the same frequency, which enables transmission/reception processing, such as multiplexing/separation of data, and insertion/extraction of information with the use of a memory, to be performed quite easily.
Referring to FIG. 5, a conventional clock signal generator includes a first inverting amplifier 51, a second inverting amplifier 52, a quartz crystal 53, a resistor R5, a resistor R6, and a capacitor C1. The resistor R6 is connected between an output end and an input end of the first inverting amplifier 51. The resistor R5 is connected between an output end and an input end of the second inverting amplifier 52. The quartz crystal 53 is connected between the input end of the first inverting amplifier 51 and the output end of the second inverting amplifier 52. The capacitor C1 is connected in series between the first inverting amplifier 51 and the second inverting amplifier 52. The output of the conventional clock signal generator is a sine wave. A computer system generally requires a rectangular wave. Therefore a conventional clock signal does not fulfill the requirements of a computer system.
What is needed is to provide a clock signal generator which can overcome the above shortcoming.